Submission #489187

#	Time	Username	Problem	Language	Result	Execution time	Memory
489187		cfalas	Dynamic Diameter (CEOI19_diameter)	C++17	42 / 100	5064 ms	35244 KiB

diameter

#include<bits/stdc++.h>
using namespace std;
#define mp make_pair
#define INF 10000000
#define MOD 1000000007
#define MID ((l+r)/2)
#define HASHMOD 2305843009213693951
#define ll long long
#define ull unsigned long long
#define F first
#define S second
typedef pair<ll, ll> ii;
typedef pair<ii, ll> iii;
typedef vector<ll> vi;
typedef vector<ii> vii;
typedef map<ll, ll> mii;

#define EPS 1e-6
#define FOR(i,n) for(int i=0;i<((int)(n));i++)
#define FORi(i,a,b) for(int i=((int)(a));i<((int)(b));i++)
#define FOA(v, a) for(auto v : a)

ll t, n;
vi a, b;

vector<vii> adj;

ii f;

ll cnt=0;
vector<int> dfso;
void dfs(int s, int p=-1, ll d=0){
	dfso[s] = cnt++;
	if(d>f.F) f = max(f, {d, s});
	FOA(v, adj[s]){
		if(v.F!=p) dfs(v.F, s, d+v.S);
	}
}

vector<int> pr;

struct node{
	ii l1={0,0}, l2={0,0};
	int w=0;
	int id=1;
	ll ans=0;
	vector<node*> c;
	vector<node*> all_c;

	void build(int p=-1){
		pr.push_back(id);
		FOA(v,adj[id]){
			if(v.F!=p){
				c.push_back(new node());
				c[c.size()-1]->w = v.S;
				c[c.size()-1]->id = v.F;
				c[c.size()-1]->build(id);
			}
		}
		FOA(v, c){
			if(v->w + v->l1.F > l1.F) l2 = l1, l1 = {v->l1.F + v->w, v->id};
			else if(v->w + v->l1.F > l2.F && v->id != l1.S) l2 = {v->l1.F + v->w, v->id};
			ans = max(ans, v->ans);
			//else if(v->w + v->l2 > l2) l2 = v->l2 + v->w;
		}
		ans = max(ans, l1.F + l2.F);
		//cout<<id<<" ("<<l1.F<<" "<<l1.S<<") ("<<l2.F<<" "<<l2.S<<")"<<" "<<ans<<endl;
	}

	void update(int s, ll t){
		int pos = c.size()-1;
		FOR(i,c.size()-1){
			if(dfso[c[i]->id] <= dfso[s] && dfso[s] < dfso[c[i+1]->id]) pos = i;
		}
		if(s==id){
			//cout<<"CHAINGE "<<s<<endl;
			w = t;
		}
		else{
			c[pos]->update(s, t);
			//node*v = c[pos];
			l1 = {0,0}, l2 = {0,0};
			ans = 0;
			FOA(v, c){
				if(v->w + v->l1.F > l1.F) l2 = l1, l1 = {v->l1.F + v->w, v->id};
				else if(v->w + v->l1.F > l2.F && v->id != l1.S) l2 = {v->l1.F + v->w, v->id};
				ans = max(ans, v->ans);
			}
			ans = max(ans, l1.F + l2.F);
			//cout<<id<<" ("<<l1.F<<" "<<l1.S<<") ("<<l2.F<<" "<<l2.S<<")"<<" "<<ans<<endl;
		}
	}
};

int main(){
	int q;
	ll w;
	cin>>n>>q>>w;
	adj.assign(n+1, vii());
	dfso.assign(n+1, 0);

	vector<pair<ii,ii> > edg(n-1);
	set<ii> ws;
	vi wu(n);
	FOR(i,n-1){
		ll a, b, c;
		cin>>a>>b>>c;
		ws.insert({-c, i});
		wu[i] = c;
		edg[i] = {{a, adj[a].size()}, {b, adj[b].size()}};
		adj[a].push_back({b,c});
		adj[b].push_back({a,c});
	}
	node root;
	root.build();
	ll last=0;
	dfs(1);
	//FOR(i,n) cout<<dfso[i+1]<<" "; cout<<endl;
	while(q--){
		ll a, b;
		cin>>a>>b;
			//cout<<"UPDATE\n";
		a= (a + last) % (n-1);
		b = (b+last) % w;

		adj[edg[a].F.F][edg[a].F.S].S = b;
		adj[edg[a].S.F][edg[a].S.S].S = b;

		f = {0,1};
		//dfs(1);
		//dfs(f.S);


		//cout<<a<<" "<<b<<endl;
		//cout<<"edg "<<edg[a].F.F<<" "<<edg[a].S.F<<endl;
		int upn = max(ii(dfso[edg[a].F.F], edg[a].F.F),ii(dfso[edg[a].S.F], edg[a].S.F)).S;
		//cout<<"pos "<<upn<<endl;
		root.update(upn, b);


		//last = f.F;
		last = root.ans;
		cout<<last<<endl;

	}
}

• Subtask 1: 11 / 11
• Subtask 2: 13 / 13
• Subtask 3: 0 / 7
• Subtask 4: 18 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27